I recently replaced my Stellarvue with a Takahashi FSQ-85 EDX on top of my C11" EdgeHD.  The mount is an AP1100.  I've have used this setup the past 2 years with NINA with issues until I replaced the Stellarvue with the Tak.  Everything works fine except for the first 5-minute frame following meridian flip, which is showing elongated stars.  Then, things settle down for the rest of the session.  All screws are tight, scope is well-balanced, cables are managed through the mount with no snags, and I cannot find any loose parts. I use an Optec ThirdLynx auto-motor focuser on the Tak, similar to the one that I used on the Stellarvue.  I've heard stories in the past of the Tak focuser slipping but the Optec autofocuser has it locked in place.  I have not had time (weather-related) to test the C11 to see if it will start doing the same thing.  I do not think it is a mount issue but I am asking here just in case someone else has experienced this and what the potential causes could be.  I guess if the C11 now starts doing this, it could be a mount problem, but I find it suspicious that it only started happening when I swapped the scopes (along with the dovetail plate and support rings).  I've attached a couple of pics of the setup but they may not help much.  

Any thoughts would be appreciated.

Bruce